BCAAs (branched-chain amino acids or branched chain amino acids) are a fantastic trio consisting of the amino acids leucine, isoleucine and valine. All three are essential amino acids, which means that the body can not only synthesize them from other amino acids, but must necessarily enter them through food or supplementation.

BCAAs make up 40% of the daily requirement of a total of 9 essential amino acids (the others are: phenylalanine, threonine, tryptophan, methionine, lysine and histidine). In addition, they make up about 35% of muscle tissue.

In food, of course, we find them in foods rich in protein, and mostly in chicken, beef, salmon, eggs, … We also find them in whey proteins (whey).

The importance of BCAA supplementation

As far as supplementation is concerned, it is of particular importance to athletes because the free form of BCAA bypasses the liver and intestine and enters the bloodstream directly. This is the reason why people with liver damage were able to maintain muscle mass when ingesting supplemental BCAAs.

BCAAs came to the market in supplementary form before some of the more popular supplements, such as creatine, and for quite a long time they were not given the importance they deserve because of their qualities. It is only in recent times that more research has been devoted to them, the results of which reveal that BCAAs are much more than ordinary protein building blocks.

When we usually talk about proteins, we primarily mean their building role, not their energy role. However, with BCAAs, their energy role is unavoidable. Unlike other amino acids, BCAAs are metabolized within the muscle, allowing the muscle to use them as energy during training in the form of ATP. There is also a bonus effect, because, not only can BCAAs be used as energy, but they promote fat oxidation (breakdown) in athletes whose glycogen reserves are depleted.

Also read: BCAAs vs EAAs – Which is better for building muscle

BCAA action

Another way in which BCAAs allow an athlete to train longer and more intensely is their effect on glycogen reserves. BCAAs have been shown to “store” glycogen and reduce its consumption by up to 25%. In this way, a faster recovery after training is enabled.

The next beneficial effect that BCAAs have is that on anabolic hormones: testosterone, insulin, and growth hormone. Normally, testosterone rises under the influence of intense training, but after training there is a drop. However, it has been found that his level remains elevated until a few hours after training if the athlete has ingested BCAAs before training.

In addition, BCAAs improve the testosterone: cortisol ratio and thus contribute to the anabolic environment. Leucine has been shown to have the potential to raise insulin sensitivity, leading to easier adipose tissue resolution, greater muscle growth, and defense against diabetes.

Recent research reveals that abstract, Sci-Fi, or long-distance activity of BCAAs and its benefits. BCAAs (especially leucine) have been found to play the role of a signaling molecule that sends a message to the body: “Build muscle!” and it works through a specific mechanism.

Namely, inside the cell there is a protein molecule mTOR (mammalian target of rapamycin or mechanistic target of rapamycin). Leucine has been shown to act as a trigger on its mTORC1 fraction, activating a complicated metabolic pathway that results in activation of protein synthesis (= new muscle tissue). Of course, everything works together if physical activity is also present, I guess it doesn’t need to be mentioned.

Leucine, if ingested after training of adequate intensity, can increase protein synthesis by up to 145%. Protein synthesis is impaired after the age of 35. Therefore, in old age, leucine is an important link in achieving a favorable environment for muscle growth (that is, in this case, the maintenance and preservation of existing muscle tissue).

BCAA and endurance training

BCAA also finds its place in endurance training. There are two mechanisms by which BCAAs improve endurance. First, BCAAs can serve as energy and thus allow for a longer duration of ATP during training that depletes glycogen reserves. Likewise, BCAAs make fats available to the body for energy purposes. Second, BCAAs prevent CNS fatigue by inhibiting tryptophan entry into the brain. Tryptophan is involved in the production of serotonin in the brain, which increases fatigue.

Also, BCAAs reduce DOMS and thus allow for a higher frequency of training and more intense training. They achieve this effect regardless of whether the person is trained or not. In one study, the group taking BCAAs subjectively had significantly reduced muscle soreness after intense training and had lower values ​​of markers of inflammation. Likewise, the BCAA group achieved recovery at maximum strength in a shorter time than the placebo group. This speaks in favor of enhanced protein synthesis in order to restore function faster.

More or less all the benefits of BCAAs are related to leucine. Therefore, the logical question is why would we supplement with all three BCAAs, when leucine is the main carrier of their positive properties? The answer is because, if we take leucine alone, the concentrations of the other two amino acids can be lowered. And it has been shown that the best results in protein synthesis are achieved when the ratio of leucine: isoleucine: valine = 2: 1: 1. In addition, isoleucine improves glucose tolerance.

One more thing to keep in mind: although BCAAs signal muscle growth, it is necessary to have a complete spectrum of amino acids as a substrate for protein synthesis in muscle to actually occur.


BCAAs are taken before, during and after training. The general recommendation is 3-5g before, during and after training. In some places, we will come across a recommendation with much higher values.

For athletes engaged in very intense training, the dose can be calculated according to the following formula: (total body weight in kg) – (adipose tissue mass in kg) X 0.44 = number of grams of BCAA per day.